Present practice in making consolidated fiber products, such as fibersheets and fiberboards, from resin-impregnated fibrous mats utilizes a hot pressing step in which the fibrous mat is subjected to pressure and a temperature in excess of that required to cure the resin for a time sufficient to cure the resin and consolidate the mat into the final fiber product of the desired thickness.
Such hot pressing is most usually carried out in intermittent-type platen presses. These are expensive to construct and operate, have long operating cycles due to the time required to open and close the platens, and lack versatility in processing fiber products of different weights and thicknesses.
Continuous hot press units are also used, but in order to effect cure of the resin in the mat these presses must be long and consequently are costly. In addition, the speed of mats through these presses is slow in order to insure a complete cure.
In short, present hot pressing procedures require expensive apparatus, lack versatility in processing, have slow processing speeds, and are not entirely suitable in making thin fiberboards or sheets.